1. Field of the Invention
This invention relates to solving problems involving a defective laser scanner in laser printers, copiers, and facsimile machines, otherwise known as imaging machines. The problems occur in a high percentage of printers, possibly as high as thirty to forty percent of the Canon SX printers in the field. The problems also occur in the popular HP Series 2 and Series 3 LASERJET printers as well as in some APPLE printers. At the time of this writing, the CANON SX engine printer is the most widely used printer worldwide. The majority of these SX printers are comprised of the mentioned HP LASERJETS Series 2 and 3. Its numbers are diminishing because the OEM manufacturers discontinued manufacturing the SX printer over three years ago. However, the number of these SX printers produced and sold was so high that they will be numerous in the field for quite some time to come. The invention of this application modifies the toner cartridge as an alternative to fixing the laser scanner by replacing the laser light beam assembly.
2. Description of the Prior Art
CANON has designed an all-in-one toner cartridge as in U.S. Pat. No. 4,975,744, issued Dec. 4, 1990 and assigned to CANON. Several companies have used these cartridges in laser printers, copy machines and facsimile machines, each with the varying printer engines and a different nameplate. Originally, these cartridges were designed to be "disposable". However, after the first all-in-one toner cartridge was introduced, it did not take long before laser cartridge remanufacturers began remanufacturing cartridges. These "disposable" cartridges were designed to funcion for only one cartridge cycle without remanufacturing. The remanufacturers had found certain components that needed replacement on a regular basis. In 1990, the first aftermarket photoreceptor drum became available for use in remanufacturing the all-in-one cartridge of the "SX" engine variety, the most popular printer cartridge from around 1987 through 1995. When the long-life photoreceptor drum became available, the entire remanufacturing industry turned around and gained great strength and began a huge growth surge that still continues. In October 1993, HEWLETT-PACKARD, the largest seller of this printer engine using the all-in-one cartridge, entered the cartridge remanufacturing industry with the "OPTIVA" cartridge, further increasing the size as well as credibility of this relatively new industry. However, this industry grew from the all-in-one cartridge shortly after its debut. Before the introduction of the long-life drum, sometimes called the "superdrum" or "duradrum", the SX cartridge would last for around three cartridge remanufaeturing cycles at best, since the maximum useful life of the OEM drum was three cycles. However, the long-life drums got their names from the fact that they were designed to last for many remanufacturing cycles or recharges as they are sometimes called. Typically, the long life drum can last for ten or more such cycles, unlike the typical OEM (Original Equipment Manufaturer) drum. With the additional developments of drum coatings, originally designed for OEM drums, the long-life drum may last for many additional cycles. Some coatings, in theory, were designed to be sacrificial, and dissolved and removed from over the drum surface every 1-3 cycles, so the drum life of the long-life drum almost seems limitless.
However, with photoreceptor drums lasting for many cycles, other components of the cartridge have a tendency to require greater durability, a better solution, or a greater life. Also, as the success of these cartridges has skyrocketed, the demand is for cartridges with longer cycles, so component improvements are significant. Therefore, avoiding natural problems with prevention means must also be implemented for cartridges of longer life both in longer cycle times and greater number of cycles.
There is a problem in around thirty to forty percent of the SX laser printers. This problem may also occur in other types of dry toner printers, copiers and facsimile machines, which will be categorized as "imaging machines" in this application. The laser light beam of the laser scanner unit hits the photoreceptor drum in areas that are not in the print region of the output page. This discharges, or punches pixels in the latent electrostatic image on the photoreceptor drum. These areas of the photoreceptor drum then attract toner. As the drum rotates, the attracted toner is scraped into the waste toner hopper of the cartridge, overfilling a region on the left side (usually) of the waste toner hopper and eventually leaking out into the imaging machine. The toner leakage causes additional problems. For example, toner spotting or streaking will develop on the left side or margin of the output page in what is supposed to be a nonprint region. The nonprint region typically consists of an one eighth inch margin around all four edges of the paper. It happens that the problem, however, is most prevalent on the left side. As the overflow from the waste toner hopper progresses, the toner spotting or streaking may enter the print region of the output paper.
The toner leakage soils the inside of the toner cartridge and the inside of the printer. Once the toner is let loose in the cartridge and printer, side effect problems may occur related to the toner landing on the corona wire, corona wire grid, corona assembly reflective walls, erase lamp, mirrors or any other components.
Cleaning up a toner mess in the toner cartridge and printer is time consuming and cumbersome. Toner cartridges thought to be defective are returned from the customers and replaced at no charge. Most printer technicians have not recognized the cause of these problems and have merely dealt with the symptoms by cleaning the printer and/or putting in a fresh toner cartridge. In fact, many technicians give the customer a free replacement cartridge because they think the problems are caused by recharged toner cartridges. Some very astute printer technicians have recognized the problem with the wobbly laser scanner assembly and have repaired or replaced the laser scanner unit in the printer. But parts and labor for replacing the toner cartridge and replacing or repairing the laser scanner unit are expensive. An improvement to the toner cartridge which prevents toner leakage and spotting or streaking on the output paper of the printer would significantly improve the operation of the cartridge and would reduce the costs of cartridge remanufacturing and printer maintenance. Furthermore, it neutralizes the detrimental effects of the defective laser scanner assembly.
U.S. Pat. No. 5,400,128, granted Mar. 21, 1995 to a coinventor of this application, is relevant for describing the operation of an imaging system.